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  • Elsevier (CrossRef)  (512)
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  • 1
    Language: English
    In: Microelectronics Reliability, September 2013, Vol.53(9-11), pp.1681-1686
    Description: In the past the main focus for improvements in power electronic modules was on chip technology. Therefore, looking at the cross section structure of modern modules, only small improvements have been made in recent decades. The reason for this is that the design and joining technology satisfied the market requirements. Furthermore the power electronic market segment is smaller than the one for microelectronic devices. Therefore it had to use their existing production facilities, e.g. bond wire machines. In the future this will change because of the following reasons: 1) Power electronic performance depends by a high ratio on package technology 2) The automotive industry has high requirements regarding cost efficiency, reliability and compactness. Furthermore they have big lever for innovations to make a product fit this requirement. Power electronic devices are used in (hybrid) electric vehicles ((H)EVs). 3) Dies in future will require new package technologies, especially when a wide band gap (WBG) material like silicon carbide (SiC) or gallium nitride (GaN) is used. Therefore there is a need for a paradigm shift in package technology to make use of a junction temperature above 200°C possible while reliability and cost performance have increased. This article will give an overview of the current available technologies and present Fuji’s new package solution ideas.
    Keywords: Engineering
    ISSN: 0026-2714
    E-ISSN: 1872-941X
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  • 2
    Language: English
    In: Journal of Hydrology, 2011, Vol.400(1), pp.58-71
    Description: ► Various methods exist to calculate hydraulic conductivity ( ) from grain size data. ► Grain size based data are suitable for a general aquifer characterization. ► Calculated proved not to be reliable enough for further stochastic analyses. ► Sample heterogeneity caused strong differences between measured and calculated ► Large uncertainties on calculated are introduced by the approximation of porosity. Determination of hydraulic conductivity ( ) and its variation in space is often a major objective of hydrogeological site investigations. However, measurement of at a high spatial resolution in sedimentary aquifers is a challenge. There are a number of field methods that can be used to determine , although they differ greatly in terms of their spatial resolution. One commonly used approach is to estimate from grain size analyses, but the reliability of the resulting estimates is unclear. The aims of this study are to compare frequently used formulas for the determination of from grain size data for a broad range of sediment types and to evaluate how well these methods predict . Sonic sampling was used to obtain minimally disturbed cores in a highly heterogeneous sedimentary aquifer and values of grain size analyses from 108 core samples were calculated. Despite the high correlation of calculated derived from different formulas, mean values differed by several orders of magnitude between the formulas. For the evaluation of the reliability of the estimates, high resolution direct push slug tests (DPSTs) were also performed in the close vicinity of the cores. A high correlation between ln( ) and ln( ) was found for most of the applied formulas. Nevertheless, sample heterogeneity, i.e. the presence of small clay layers in a generally highly permeable sample, led to estimates that were significantly smaller than the estimates. Based on these results, the applied formulas appear to be suitable for an initial assessment of aquifer . However, considering the difference in calculated mean values, results are not sufficiently reliable for the high resolution analyses of variations needed for flow or transport modeling.
    Keywords: Hydraulic Conductivity ; Sieve Analysis ; Grain Size Distribution ; Direct Push Slug Test ; Sonic Sampling ; Bitterfeld ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 3
    Language: English
    In: Microelectronics Reliability, September 2014, Vol.54(9-10), pp.1901-1905
    Description: For the task of improving the reliability and robustness of power electronic semiconductor devices, the main focus is on packaging and joining technology. The improvement is made necessary by various applications which require higher active and passive temperature cycles capability. For example: Automotive applications require a minimum life time of 15 years, wind power 25 and traction applications, 30–40 years and longer. Furthermore, higher reliability is demanded of new semiconductor technology, because maximum junction temperatures will, sooner or later, exceed currently recognized limits. In the near future, silicon devices will reach a maximum junction temperature of up to 200 °C. And the new wideband-gap devices have the potential to exceed even this limit. That is why a new package and joining technology is mandatory. There are new developments in the pipeline: For the die contact, planar wire technology and copper based bond wires can be expected in the long term. This new technology is based on new material science and printed circuit board process techniques. As a robust joining method, sinter or diffusion solder will be in use soon. But on the semiconductor module level, further action can be taken now, or in the near future, to increase reliability significantly. This paper presents improvements, based on material science, which are already available and can be used now, or in the near future.
    Keywords: Power ; Electronic ; Packaging ; Joining ; Material ; Microstructure ; Engineering
    ISSN: 0026-2714
    E-ISSN: 1872-941X
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  • 4
    Language: English
    In: Best Practice & Research Clinical Gastroenterology, August 2014, Vol.28(4), pp.637-653
    Description: Nonalcoholic fatty liver disease (NAFLD) is now recognized as the most common cause of chronic liver disease worldwide. Its prevalence has increased to more than 30% of adults in developed countries and its incidence is still rising. The majority of patients with NAFLD have simple steatosis but in up to one third of patients, NAFLD progresses to its more severe form nonalcoholic steatohepatitis (NASH). NASH is characterized by liver inflammation and injury thereby determining the risk to develop liver fibrosis and cancer. NAFLD is considered the hepatic manifestation of the metabolic syndrome. However, the liver is not only a passive target but affects the pathogenesis of the metabolic syndrome and its complications. Conversely, pathophysiological changes in other organs such as in the adipose tissue, the intestinal barrier or the immune system have been identified as triggers and promoters of NAFLD progression. This article details the pathogenesis of NAFLD along with the current state of its diagnosis and treatment.
    Keywords: Nonalcoholic Fatty Liver Disease (Nafld) ; Nonalcoholic Steatohepatitis (Nash) ; Metabolic Syndrome ; Medicine
    ISSN: 1521-6918
    E-ISSN: 1532-1916
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  • 5
    Language: English
    In: Journal of Hydrology, 19 September 2014, Vol.517, pp.54-63
    Description: Aquifer storage and recovery (ASR) methods are increasingly used to overcome the temporal imbalance between water demand and availability. Common ASR recharge methods utilize large-diameter injection wells or surface infiltration basins and trenches, and can be costly to implement. A new low-cost ASR recharge method is currently being developed. This approach is based on recharge via gravity in small-diameter wells installed with direct-push (DP) technology. Numerical modeling is used here to assess the potential of this new approach under conditions commonly faced in field settings. The primary objective is to investigate if a battery of small-diameter DP wells can serve as a viable alternative to a surface basin under typical field conditions, while the secondary objective is to assess which subsurface parameters have the greatest control on DP well performance. Simulation results indicate that gravity recharge via small-diameter wells appears to have a distinct advantage over recharge via surface infiltration basins. For example, two 0.05-m shallow vadose-zone wells with 9-m screens can recharge water at a greater rate than a 60 m basin. Also, results reveal that, contrary to an infiltration basin, the recharge rate in a DP well has a much stronger dependence on the horizontal component of hydraulic conductivity than on the vertical component. Moreover, near-surface layers of low hydraulic conductivity, which can significantly reduce the recharge capacity of a surface basin, have a relatively small impact on the recharge capacity of a well as long as a significant portion of the well screen is installed below those layers. Given that installation and operation costs can be low in comparison to common ASR recharge methods, this new approach appears to have great potential for recharging good quality water in shallow unconsolidated aquifers. A field investigation has recently been initiated to follow up the findings of this simulation assessment.
    Keywords: Aquifer Storage and Recovery ; Direct-Push ; Artificial Recharge ; Groundwater Modeling ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 6
    Language: English
    In: Journal of Hydrology, 24 July 2013, Vol.496, pp.195-204
    Description: The characterization of hydraulic conductivity ( ) variations in heterogeneous aquifers has proven to be a significant challenge. Recent field and numerical assessments, however, have demonstrated the considerable potential of direct-push profiling for characterization of vertical variations at the resolution needed for contaminant site investigations. The direct-push permeameter (DPP), in particular, has been found to be an effective characterization tool (0.4-m resolution in current configuration) over the range expected in aquifers. The potential of this tool is explored further here through numerical simulations to assess the probe configuration and the analysis approach that are most appropriate for profiling in highly permeable heterogeneous systems. A probe configuration with transducers placed between 0.1 and 0.4 m from the injection screen appears to be most suitable for general field applications, as it can yield a reasonable resolution (few decimeters) in the presence of a typical level of sensor noise. DPP data are commonly analyzed using the spherical form of Darcy’s Law. Although this approach will provide reliable estimates in many situations, it can introduce error in the presence of thin (relative to the distance between injection screen and transducers) layers of vastly differing . Simultaneous numerical inversion (under steady-shape conditions) of all DPP tests in a profile can yield improved results if information about aquifer structure is available. DPP estimates have little sensitivity to the zone of compaction created during probe advancement, but estimates are sensitive to channeling along the probe surface. Proper probe design (probe shape and position of transducers) and test procedures (low injection rates) can reduce the potential for and impact of such channeling. These points are demonstrated using data from an outcrop study in which varies by orders of magnitude on the scale of a few decimeters.
    Keywords: Direct-Push Permeameter ; Hydraulic Conductivity ; Numerical Simulation ; High-Resolution Profiling ; Site Characterization ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 7
    Language: English
    In: The Journal of Urology, April 2016, Vol.195(4), pp.e744-e745
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.juro.2016.02.613 Byline: Michael Avallone, Peter Dietrich, Shanta Shepherd, Mona Lalehzari, R. Corey O'Connor, Michael Guralnick Author Affiliation: Milwaukee, WI Article Note: (footnote) Source of Funding: None
    Keywords: Medicine
    ISSN: 0022-5347
    E-ISSN: 1527-3792
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  • 8
    Language: English
    In: Journal of Hydrology, March 2016, Vol.534, pp.113-123
    Description: The ongoing transition from fossil fuels to alternative energy source provision has resulted in increased geothermal uses as well as storage of the shallow subsurface. Existing approaches for exploration of shallow subsurface geothermal energy storage often lack the ability to provide information concerning the spatial variability of thermal storage parameters. However, parameter distributions have to be known to ensure that sustainable geothermal use of the shallow subsurface can take place – especially when it is subject to intensive usage. In this paper, we test a temperature decay time approach to obtain , direct, qualitative, spatial high-resolution information about the distribution of thermal storage capabilities of the shallow subsurface. To achieve this, temperature data from a high-resolution Fibre-Optic-Distributed-Temperature-Sensing device, as well as data from conventional Pt -temperature-sensors were collected during a heat injection test. The latter test was used to measure the decay time of temperature signal dissipation of the subsurface. Signal generation was provided by in-aquifer heating with a temperature self-regulating electric heating cable. Heating was carried out for 4.5 days. After this, a cooling period of 1.5 weeks was observed. Temperature dissipation data was also compared to Direct-Push-derived high-resolution (hydro-)geological data. The results show that besides hydraulic properties also the bedding and compaction state of the sediment have an impact on the thermal storage capability of the saturated subsurface. The temperature decay time approach is therefore a reliable method for obtaining information regarding the qualitative heat storage capability of heterogeneous aquifers for the use with closed loop system geothermal storage systems. Furthermore, this approach is advantageous over other commonly used methods, e.g. soil-sampling and laboratory analysis, as even small changes in (hydro-)geological properties lead to strong variances in observed heat-storage capabilities at the investigated case study site. By using fibre-optic-thermometers, nearly every requested spatial resolution can be achieved and easily be adjusted to the needs of actual test sites for shallow geothermal storage exploration.
    Keywords: Distributed-Temperature-Sensing ; Shallow Subsurface Thermal-Storage ; Shallow Geothermal Exploration ; Direct-Push in Situ Investigations ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 9
    Language: English
    In: Journal of Contaminant Hydrology, 2011, Vol.122(1), pp.1-15
    Description: Measuring contaminant flow rates at control cross sections is the most accurate method to evaluate natural attenuation processes in the saturated subsurface. In most instances, point scale measurement is the method of choice due to practical reasons and cost factors. However, at many field sites, the monitoring network is too sparse for a reliable estimation of contaminant and groundwater flow rates. Therefore, integral pumping tests have been developed as an alternative. In this study, we compare mass flow rates obtained by integral pumping test results and point scale data. We compare results of both methods with regard to uncertainties due to estimation errors and mass flow estimations based on two different point scale networks. The differences between benzene and groundwater flow rate estimates resulting from point scale samples and integral pumping tests were 6.44% and 6.97%, respectively, demonstrating the applicability of both methods at the site. Point scale-based data, especially with use of cost efficient Direct-Push technique, can be applied to show the contaminant distribution at a site and may be followed by a denser point scale network or an integral method. Nevertheless, a combination of both methods decreases uncertainties.
    Keywords: Integral Pumping Test ; Point Scale Measurements ; Cstream ; Mass Flow Rate ; Btex ; Direct-Push ; Engineering ; Environmental Sciences ; Geography
    ISSN: 0169-7722
    E-ISSN: 1873-6009
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  • 10
    Language: English
    In: Journal of Applied Geophysics, November 2015, Vol.122, pp.210-217
    Description: Systematic decomposition and evaluation of existing sensor systems as well as the optimal design of future generations of direct push probes are of high importance for optimized geophysical experiments since the employed equipment is a constrain on the data space. Direct push technologies became established methods in the field of geophysical, geotechnical, hydrogeological, and environmental sciences for the investigation of the near subsurface. By using direct push sensor systems it is possible to measure in-situ parameters with high vertical resolution. Such information is frequently used for quantitative geophysical model calibration of interpretation of geotechnical and hydrological subsurface conditions. Most of the available direct push sensor systems are largely based on empirical testing and consecutively evaluated under field conditions. Approaches suitable to identify specific characteristics and problems of direct push sensor systems have not been established, yet. We develop a general systematic approach for the classification, analysis, and optimization of direct push sensor systems. First, a classification is presented for different existing sensor systems. The following systematic description, which is based on the conceptual decomposition of an existing sensor system into subsystems, is a suitable way to analyze and explore the transfer behavior of the system components and therefore of the complete system. Also, this approach may serve as guideline for the synthesis and the design of new and optimized direct push sensor systems.
    Keywords: Direct Push (Dp) ; Optimized Experimental Design ; Subsurface Characterization ; Sensor System ; System Analysis ; Measurement Modeling ; Engineering
    ISSN: 0926-9851
    E-ISSN: 1879-1859
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